JP6272275B2 - Digital printing of plastic containers - Google Patents

Description

(Related application)
This application is provided with the benefit of US Patent No. 11 / 562,655, filed November 22, 2006, which is incorporated herein by reference.
(Technical field)
The present invention generally relates to a plastic container (plastic container) having a printed digital image thereon, in particular a container with a curved surface, and a method for printing an image on a plastic container.

  The prior art for printing on the curved surface of a plastic container has some limitations and disadvantages. This type of technology makes it difficult to provide commercially acceptable images on containers, especially containers having surfaces that are non-planar (not planar). Further, there is a need for a technique for efficiently providing a multicolor digital image (digital image) on a container at an acceptable speed and reasonable cost.

The present invention provides a technique for printing one or more digital images on a container having a non-planar outer surface. Digital images are printed on a container by applying ink droplet technology. The ink droplets vary in diameter from about 10 to about 200 μm , and the droplets are distributed from about 200 to about 1200 droplets per 2.54 cm ( inches ). Droplets are used. A method for digital printing on plastic containers is also disclosed.

It is the perspective view seen from the upper surface which illustrated the pattern of the droplet of the ink apply | coated or apply | coated to apply | coat to the surface which is the non-planar surface of the container concerning the Example of this invention, or adheres. It is the side view which showed a series of ink droplets which have an overlap part. It is a side view of the ink droplet which illustrated the magnitude | size of the related thru | or corresponding angle. It is a schematic explanatory drawing of the ink droplet application system concerning the example of the present invention. FIG. 3 is a schematic explanatory view showing a part of a printing subsystem according to an embodiment of the present invention. It is a printing subsystem schematic explanatory drawing concerning the Example of this invention. FIG. 4 is a side view of ink droplets (small droplets) applied or adhered to a base coat.

  Hereinafter, embodiments or examples of the present invention will be described with reference to the accompanying drawings.

  Examples of the present invention will be described in detail. An example of an embodiment is illustrated in the accompanying drawings and will be described below. The present invention will be described with reference to examples, but the present invention is not limited to these examples. On the other hand, the present invention covers a range of alternatives, modifications and equivalents included in the technical idea and scope of the invention limited by the appended claims.

  FIG. 1 schematically illustrates a portion of a container 10 having a non-planar surface 20. A plurality of ink droplets (small droplets, particles) 30 are shown dispersed on the surface 20 of the container. The ink droplets or ink droplets 30 gather to form part of the coating pattern, while this coating pattern forms all or part of a predetermined digital image. The application pattern may be in the form of a lattice pattern or a lattice pattern, for example, the illustrated lattice pattern, or another management or prescribed application pattern instead. Further, as schematically shown, one or more adjacent ink droplets 30 overlap (overlap) or mix (mix) with each other to form an overlapping portion 32.

  FIG. 2 is a side view of a series of ink droplets 39 with overlapping portions 32, showing adjacent regions 34 of ink. Viewed from a cross-section, adjacent regions of ink extend from a first drop end (droplet end) 36 to a second drop end 38. As better shown in FIG. 3, in some embodiments, the contact angle (edge angle) of the ink droplets represented by ink droplets 30a and 30b in the figure is from about 5 degrees to about 25 degrees. Distributed. Further, in certain embodiments, the contact angle is distributed between about 12 degrees and 15 degrees.

  Depending on the desired or desired digital image, a variety of known, including primary or basic printing colors such as cyan (red-green), magenta (red-purple) and yellow, depending on the individual ink droplets. The color is composed. Furthermore, additional or additional process colors can be provided in the overlap region 32 by adjusting or controlling the overlay or combination of specific colors in the overlap region. The ink droplets may be curable (curable). For example, all or part of the digital image may be constituted by droplets of UV curable (ultraviolet curable) ink.

Individual ink droplets 30, including those associated with a single digital image, can vary in diameter D from about 10 μm to about 200 μm . In certain embodiments, the droplet diameter D can range from about 30 μm to about 90 μm . The application of the droplets of ink provided on the surface of the container to form a digital image, 2.54 cm (inch) the number of drops per (DPI) from about 200 to about 1200, that is from about 200 to about 1200 drops / It is 2.54 cm ( inch ) , and in the embodiment, it may be 300 DPI to 1200 DPI. The resulting digital image formed on the container surface is, for example, but not limited to, in the form of a label, including text and / or colored text (lexical) and graphics (graphics and images). Or graphics can be included.

  An ink droplet application system 40 according to an embodiment of the present invention is shown in FIG. As schematically illustrated, a plurality of containers 10 including (or possibly including) a non-planar (eg, ellipsoidal, spherical, or simply regular curved) surface 20 is transported or transported to and from the printing subsystem. Pass 50. The print subsystem includes one or more print heads 60, at least one actuator 70 for controlling the vertical position of the print head relative to the container, and one or more print heads for supplying one or more types of color inks. A supply device 62 and a temperature control device 64 having a function of adjusting or controlling at least a part of the ink temperature are included, and a plurality of fluid lines 66 can also be included.

  In some embodiments, the temperature control device can include a fluid heating unit and one or more pumps that circulate heated water or other fluid. If necessary, the fluid may be circulated in a closed circuit. FIG. 5 shows an embodiment of the system 40, wherein each print head 60 is supplied with ink through an ink line (ink piping) 65 and includes, for example, a plurality of water lines (water piping). The water line can include circuitry and also includes an input line 66a and a supply return line 66b. In the embodiment, the water line (for example, the return line 66 b) wraps around the ink line 65. If necessary, a fluid line such as the illustrated water line 66b may wrap around the ink line 65 between the ink source and the print head. Alternatively, the fluid flow may be reversed and the input fluid line may be line 66b and the output fluid line 66a. In any event, such a fluid line helps to maintain the ink at the desired temperature throughout the system as the associated print head moves up and down.

  Ink is maintained in the print head at a specific temperature to a desired temperature range to supply ink droplets to the surface of the container to be processed. In an embodiment of the present invention, the ink is maintained at a temperature of about 40 ° C. to about 50 ° C. within the print head (ie, immediately before dispersion or application).

  In FIG. 4, each container 10 is schematically shown as being carried by a conveyor. However, it is important that the present invention is not limited to such means of transport. That is, the surface to be printed is not obstructed or obstructed by the print head 60 during operation, and the position of the surface to be printed can secure a sufficient space for the printing subsystem so that a controlled distance from the surface is obtained. Each container may be transported past the printing subsystem 50 using other methods and other container handling techniques, provided that the print head can be positioned to maintain. For example, without limitation, each container may be temporarily held in a fixture or holder that passes through the print head.

  The application system 40 may additionally include a scanning device (scanning device, reading device) 80 such as a laser scanner. The scanning device 80 is used to scan the printed surface of each container before the container passes through the printing subsystem 50. The scanning device 80 can capture surface profile data for the surface of the container to be printed, including, for example, surface variation (variation) and curvature (bending, curvature) data. In an embodiment, the scanned surface data is communicated to signal conditioner 82, which condition adjusts the data and communicates the data or adjusted data to processor 84. The processor 84 processes the information and provides motion control signals to the motion controller 86, which controls one or more print heads 60 (in relation to and in conjunction with the moving container surface) at the required location. A control signal is supplied to the actuator 70 for positioning in time.

  Here, it is important that the application system 40 is not limited to a configuration having independent individual scanning devices, signal conditioners, processors, motion controllers, and / or actuators. That is, within the scope of the technical idea of the present invention, these components are provided in various combinations, or these functions can be combined in various operative combinations. For example, in the simplest embodiment, the scanning device creates container surface data and communicates this data directly or indirectly to the print head (or actuator or controller that controls the position of the print head). Thus, the distance between the print head and the surface of the container to be printed is controlled as the container passes the print head.

  The printing subsystem controls the position of each print head 60, thereby ensuring that a defined or controlled offset amount relative to the surface of the container is maintained, even for non-planar surfaces. For example, as schematically illustrated in the system embodiment shown in FIG. 6, the system 40 includes a stand between a portion of a print head that dispenses or ejects ink and a surface of a container that receives ink droplets. The off-distance SD is configured to be maintained at 1 mm ± 0.3 mm. Here, in an embodiment of the present invention, the standoff distance SD is the distance between the portion of the print head 60 that supplies ink (when ink is applied) and the surface of the container that receives ink droplets. It can be said that it is particularly relevant. That is, a portion of the print head that does not coincide with a portion of the print head to which ink is applied may enter a space associated with or corresponding to the standoff distance SD. However, it is assumed that no physical interference or collision occurs between the print head and the container due to such intrusion.

  With further reference to FIG. 4, in an embodiment of the system 40, each container passes through the print head at a constant or substantially constant speed. However, embodiments of the system may include sensors that determine, monitor and / or control the speed of movement of each container (ie, speed V) in one or more stages or stages within the system. good. The system 40, for example, supplies this information to a processor or controller to coordinate or synchronize the operation of the print head to adjust for constant or non-constant movement of the container through the print head. In addition, one or more feedback control systems can be incorporated into the system to provide such control functions and to adjust or coordinate the position and operation of the print head relative to the container passing through the print head.

  In certain applications, the container may be pretreated before entering the printing subsystem 50. The pretreatment is used, for example, to increase the temperature of the surface of the container to enhance the adhesion or bonding of ink droplets. Some known pretreatment techniques include, but are not limited to, flame treatment, corona treatment, and plasma treatment. However, the present invention is not limited to these pretreatment options.

  In addition, the system 40 provides a base coat application to a portion of the surface of the container prior to printing the digital image. For example, FIG. 7 schematically shows a side view of an ink droplet 30 applied to the base coat 90. In the figure, the contact angle (or end angle) of the droplet is specified by an arrow 92a, and the contact angle of the base coat is specified by an arrow 92b. In some embodiments, the contact angle associated with the ink droplet and / or basecoat is between about 5 degrees and about 25 degrees, and for certain applications both (both angles) are about 12 degrees and about 15 degrees. Between. The base coat functions to improve the application of ink droplets and / or is composed of materials to provide visual properties. If necessary, all or part of the base coat may be digitally printed on at least a portion of the surface of the container. In an embodiment of the invention, one or more digital images are all printed on the base coat. Further, in some applications, a portion of the base coat and / or a portion of the surface of the container may be formed from a portion of the digital image. For example, if the required digital image contains a color that matches or harmonizes well with the color of the surface of the container or base coat (if applicable), the ink distribution should be controlled and avoided in such areas. The printing system can be programmed.

  Referring again to FIG. 4, the system 40 may further include means for curing the ink droplets associated with the digital image. For example, when applying UV curable ink, the means for curing includes one or more UV lamps (ultraviolet lamps) 100. Furthermore, the digital image printed on the surface of the container is formulated to cure within a defined time period. For example, in an embodiment, the digital image is cured between 0.5 and 5 seconds after the ink droplet contacts the surface of the container.

  The application system 40 may further include a post-print scanner (not shown) that scans the final digital image. The system then evaluates the post-print data to assess whether an image printed on a given container meets predetermined or set criteria, which criteria are usually related to image quality. Yes. If the image printed on the container does not meet this predetermined or established criteria, a notification will be made (alarm or operator notification) and the container will be sent to an area for further assessment and disposal or rework. .

  The foregoing descriptions of specific examples or embodiments of the present invention are intended to be illustrative and illustrative, and are not intended to limit the present invention to the forms described. Various changes and modifications are possible. Each embodiment has been chosen and described in order to explain the principles of the invention and its practical application, and those skilled in the art will appreciate that various embodiments and variations suitable for the particular king intended. Can be used. The scope of the present invention is defined by the appended claims and their equivalents.

DESCRIPTION OF SYMBOLS 10 Container 20 Surface 30, 30a, 30b Droplet 40 Ink droplet application system 50 Printing subsystem 60 Print head

Claims (14)

A container having a non-planar outer surface (20) and a digital image formed by ink droplets (30);
The ink droplets (30) vary in diameter from 10 to 200 μm, and the ink droplets are distributed from 200 to 1200 droplets per 2.54 cm (inch);
The container contains a base coat,
The base coat is a digitally printed base coat;
The digital image is printed on at least a portion of the base coat ;
Some of the base coat that form a part of the digital image, plastic containers.   A container according to claim 1, wherein the ink droplets (30) vary in diameter from 30 to 90 μm.   A container according to claim 1, wherein the ink droplets (30) are distributed between 300 and 1200 drops per inch.   The container of claim 1, wherein the ink droplet (30) spreads on the surface of the container and a portion of the droplet (30) overlaps an adjacent droplet (32).   The container according to claim 1, wherein the ink droplets are provided in a grid pattern.   The container of claim 1 wherein the angle of the ends (36, 38) of the ink droplets (30a, 30b) is from about 5 to about 25 degrees.   The container of claim 1, wherein the angle of the ends (36, 38) of the ink droplets (30a, 30b) is from about 12 to about 15 degrees.   The container of claim 1, wherein the digital image has multiple colors.   The container of claim 1, wherein adjacent portions of ink droplets (30) overlap to provide one or more process colors.   The container of claim 1, wherein at least some of the ink droplets (30) are UV curable.   A container according to claim 1, wherein the ink droplet (30) defines a predetermined image on the surface of the container.   The container of claim 1, wherein the entire digital image is printed on the base coat.   The container of claim 1, wherein a portion of the surface of the container provides a portion of the color that forms part of the digital image.   A container according to claim 1, wherein the outer surface of the container is a curved outer surface (20).

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